A Novel Hybrid Random Copolymer PoIy(MAPOSS-c0-NIPAM-c0-OEGMA-c0-2VP): Synthesis. Characterization, Self-Assembly Behaviors and Multiple Responsive Properties

摘要

A novel organic/inorganic hybrid amphophilic random copolymer poly(methacrylate isobutyl POSS-co-N-isopropylacrylamide-ro-oligo(elhylene glycol) methyl ether methacrylate-co-2-vmylpyridine), poly(MAPOSS-co-NIPAM-co-OFGMA-co-2 VP), was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The self-assembly behavior of random copolymers in aqueous solution was investigated by dynamic light scattering (DLS) as well as transmission electron microscopy (TEM). The results indicate the novel random copolymer in water could self-assemble into spherical aggregates and the self-aggregate size displays a remarkable dependence on pH. The stimuli-responsive characteristics of these assembles were tested by means of UV-vis spectra, DLS and TVM. There is a critic Zn~(2+) concentration over which the aggregates can be coordinated into well-define spherical aggregate clusters. The critic Zn~(2+) concentration can be tuned finely through adjusting solution concentration or 2VP amount. Results from U V-vis and DLS reveal that the copolymer solutions exhibit a sharp and intensive lower critical solution temperature (LCST). Some factors such as the solution concentration, molecular weight, pH and copolymer generation, which could affect the cloud point, were studied systematically. The essentially predetermined LCST can be achieved by altering the content of 2VP orpH. In addition, these novel hybrid aggregates can undergo an association/disassociation cycle with the heating and cooling of solution and the degree of reversibility shows a strong concentration dependence. As a novel organic-inorganic hybrid material which can respond to multiple external stimuli including temperature, pH, metal ions with sharp stimuli-responsive behaviors, it is potentially used for biomedicine, catalysis, diagnostics, bioseparalions, biosensors and for fundamental investigation.